Pen



FIG. 1 is a perspective view of a pen showing a new design;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a left view thereof;

FIG. 5 is an enlarged top view thereof; and,

FIG. 6 is an enlarged bottom view thereof. 

CLAIM The ornamental design for a “pen,” as shown and described. 